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Bias Tees / DC Blocks

Bias Tees

An RF/microwave bias tee is a device that combines (or separates) a DC signal with an RF signal, generally for biasing amplifiers or other active microwave devices. Our bias tees offer low insertion loss and high return loss to from kHz to Ka band frequencies. They are available in connectorized, surface mount, and RoHS surface mount versions. The surface mount bias tees come in an extremely compact .150” x .240” package.

Marki offers two basic designs for surface mount bias tees. The design used only in the BT-0030SM/G, includes a bypass capacitor on the DC input line, making it immune to external disturbances on the bias line, but it also cannot be improved with additional external components. The performance of the BT-0030SM/G does not change with the current load on the DC bias line. The design used in the BT-0014SM/G, BT-0024SM/G, and BT-0034SM/G does not include an internal bypass capacitor directly on the DC blocking line. The low frequency on these bias tees is lower (500 kHz instead of 10 MHz), but is dependent on the bias conditions. It can be extended lower and made more insensitive to current with an external coil (down to 4 kHz). An external bypass capacitor can also be added to make it more immune to bias line disturbances.